NAME
Business::Inventory::Valuation - Calculate inventory value/unit price
(using LIFO/FIFO/weighted average)
VERSION
This document describes version 0.007 of Business::Inventory::Valuation
(from Perl distribution Business-Inventory-Valuation), released on
2018-03-17.
SYNOPSIS
use Business::Inventory::Valuation;
my $biv = Business::Inventory::Valuation->new(
method => 'LIFO', # required. choose LIFO/FIFO/weighted average
#allow_negative_inventory => 0, # optional, default 0
);
my @inv;
# buy: 100 units @1500
$biv->buy(100, 1500);
@inv = $biv->inventory; # => ([100, 1500])
say $biv->units; # 100
say $biv->average_purchase_price; # 1500
# buy more: 150 units @1600
$biv->buy(150, 1600);
@inv = $biv->inventory; # => ([100, 1500], [150, 1600])
say $biv->units; # 250
say $biv->average_purchase_price; # 1560
# sell: 50 units @1700. with LIFO method, the most recently purchased units are sold first.
$biv->sell( 50, 1700); # returns two versions of realized profit & actual units sold: (7000, 5000, 50)
@inv = $biv->inventory; # => ([100, 1500], [100, 1600])
say $biv->units; # 200
say $biv->average_purchase_price; # 1550
# buy: 200 units @1500
$biv->buy(200, 1500);
@inv = $biv->inventory; # => ([100, 1500], [100, 1600], [200, 1500])
say $biv->units; # 400
say $biv->average_purchase_price; # 1550
# sell: 350 units @1800
$biv->sell(350, 1800); # returns two versions of realized profit & actual units sold: (96250, 95000, 350)
@inv = $biv->inventory; # => ([50, 1500])
say $biv->units; # 50
say $biv->average_purchase_price; # 1500
($units, $avgprice) = $biv->summary; # => (50, 1500)
# sell: 60 units @1700
$biv->sell(60, 1700); # dies! tried to oversell more than available in inventory.
With FIFO method, the most anciently purchased units are sold first:
my $biv = Business::Inventory::Valuation->new(method => 'FIFO');
$biv->buy(100, 1500);
$biv->buy(150, 1600);
$biv->sell(50, 1700); # returns two versions of realized profit & actual units sold: (7000, 10000, 50)
@inv = $biv->inventory; # => ([50, 1500], [150, 1600])
say $biv->units; # 200
say $biv->average_purchase_price; # 1575
With "weighted average" method, each purchase will be pooled into a
single group with purchase price set to average purchase price:
my $biv = Business::Inventory::Valuation->new(method => 'weighted average');
$biv->buy(100, 1500);
@inv = $biv->inventory; # => ([100, 1500])
say $biv->units; # 100
say $biv->average_purchase_price; # 1500
$biv->buy(150, 1600);
@inv = $biv->inventory; # => ([250, 1560])
say $biv->units; # 250
say $biv->average_purchase_price; # 1560
$biv->sell( 50, 1700); # returns: (7000, 7000, 50)
@inv = $biv->inventory; # => ([200, 1560])
say $biv->units; # 200
say $biv->average_purchase_price; # 1560
Overselling is allowed when "allow_negative_inventory" is set to true.
Amount sold is set to the available inventory and inventory becomes
empty:
my $biv = Business::Inventory::Valuation->new(
method => 'LIFO',
allow_negative_inventory => 1,
);
$biv->buy(100, 1500);
$biv->buy(150, 1600);
$biv->sell(300, 1700); # returns two versions of realized profit & actual units sold: (35000, 35000, 250)
@inv = $biv->inventory; # => ()
say $biv->units; # 0
say $biv->average_purchase_price; # undef
DESCRIPTION
This class can be used if you want to calculate average purchase price
from a series of purchases each with different prices (like when buying
stocks or cryptocurrencies) or want to value your inventory using
LIFO/FIFO method.
Keywords: average purchase price, inventory, inventory valuation, cost
accounting, FIFO, LIFO, weighted average, COGS, cost of goods sold.
METHODS
new
Usage: Business::Inventory::Valuation->new(%args) => obj
Known arguments ("*" denotes required argument):
* method* => str ("LIFO"|"FIFO"|"weighted average")
When the method is "LIFO" or "FIFO", the class will keep track of
each purchase at different prices. Then when there is a selling, the
units that are most recently purchased (in the case of FIFO) or most
anciently purchased (in the case of "LIFO") will be subtracted
first.
When the method is "weighted average", each purchase will be mixed
into a single pool with the purchase price being calculated at
average purchase price.
* allow_negative_inventory => bool (default: 0)
By default, when you try to "sell()" more amount than you have
bought, the method will die. When this argument is set to true, the
method will not die but will simply ignore then excess amount sold
(see "sell" for more details).
buy
Usage: $biv->buy($units, $unit_price) => num
Add units to inventory. Will return average purchase price, which is
calculated as the weighted average from all purchases.
sell
Usage: $biv->sell($units, $unit_price) => ($profit1, $profit2,
$actual_units_sold)
Take units from inventory. If method is FIFO, will take the units
according to the order of purchase (units bought earlier will be taken
first). If method is LIFO, will take the units according to the reverse
order of purchase (units bought later will be taken first).
Will die if $units exceeds the number of units in inventory
(overselling), unless when "allow_negative_inventory" constructor
argument is set to true (see "new") which will just take the inventory
up to the amount of inventory and set the inventory to zero.
$unit_price is the unit selling price.
Will return a list containing two versions of realized profits as well
actual units sold. The first element is profit calculated using weighted
average method: ($unit_price - *average-purchase-price*) x *units-sold*.
The second element is profit calculated by the actual purchase price of
the taken units (in the case of LIFO or FIFO). When method is `weighted
average', the first element and second element will be the same. Actual
units sold can be different from $units if there is overselling, since
we subtract only with the available units in inventory.
To calculate the COGS (cost of goods sold), you can use:
$units*$unit_price - $profit2
units
Usage: $biv->units => num
Return the current number of units in the inventory.
If you want to know each number of units bought at different prices, use
"inventory".
average_purchase_price
Usage: $biv->average_purchase_price => num
Return the average purchase price, which is calculated by weighted
average.
If there is no inventory, will return undef.
inventory
Usage: $biv->inventory => @ary
Return the current inventory, which is a list of "[units, price]"
arrays. For example if you buy 500 units @10 then buy another 1000 units
@12.5, "inventory()" will return: "([500, 10], [1000, 12.5])".
HOMEPAGE
Please visit the project's homepage at
.
SOURCE
Source repository is at
.
BUGS
Please report any bugs or feature requests on the bugtracker website
When submitting a bug or request, please include a test-file or a patch
to an existing test-file that illustrates the bug or desired feature.
SEE ALSO
AUTHOR
perlancar
COPYRIGHT AND LICENSE
This software is copyright (c) 2018 by perlancar@cpan.org.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.